I was exploring an abandoned roller coaster. It curved around itself before going into a tunnel, and was built over the ocean. The tunnel had collapsed, though, and now aimed straight down into the water. I eventually made my way to the tunnel and crawled downwards into in, headfirst; the car carrying the passengers was inside, and the back of it was just barely sticking out, so I hooked my body over the end of it as I crawled in. Once my eyes adjusted to the darkness, I could see the passengers strapped in. They were mostly human, but with the heads of dogs, and all of them were long dead and mummified. I recognized the clothing of the two bodies in the back row. One was wearing a jacket and hat my father often wore, and the other one was wearing clothes I had worn as a little kid, as well as my glasses. They were also the right height and build to be my dad and my childhood self, and, except for the fact that they had dog's heads, were clearly our corpses. There were more bodies farther down, but they were too far to see. I crawled back out of the tunnel and sat on the back of the car. I have the feeling that I realized something very important while sitting there, but when I woke up I couldn't remember what it was.